The present invention relates to a process for developing a two-component diazocopying material with a gas which has been released by evaporation of a developing liquid, more especially an aqueous ammonia solution. In particular, the gas is an ammonia-steam mixture. In this process, the temperature in the developing zone is higher than the temperature of admission from the evaporation zone. Furthermore, the invention relates to an apparatus for carrying out this process.
When a copying material of this type is developed with an ammonia-steam mixture, the general procedure consists in leading the copying material through a developing zone at the bottom of which an evaporator is arranged. A developing liquid is dripped into the evaporator, and the developing gas is released out of the developing liquid by the action of heat. It is a disadvantage that part of the steam which is in the developing gas precipitates on the conveyor belt or on the conveyor rolls as well as on the copying material. The condensed water can moisten the copying material and loosen the binding agent of the light-sensitive layer. As a result, the copying material can possibly stick to the structural parts of the developing zone and can cause break-down and jamming.
The process mentioned in the first paragraph, which is known from German Offenlegungsschrift No. 2,417,979, is intended to solve this disadvantage. In this process, the concentration of the developing gas can be maintained at a constant value, and the developing gas does not condense in the developing zone. The process is suitably carried out in such a way that the entering temperature of the admitted developing gas as well as the temperature of the developing zone are kept at a constant value or in such a way that both temperatures vary according to the same function. The known apparatus for carrying out this process comprises a vessel which contains the developing liquid and a developing zone which is provided with a heater and which can be closed. The developing zone is linked to the vessel by pipe-lines. A pump and a gas-expelling chamber which is provided with a heater, are connected to the developing zone. The heater of the developing zone is connected to a first temperature control device, the heater of the gas-expelling chamber is connected to a second temperature control device, and the set point of the first temperature control device is set higher than the set point of the second temperature control device.
In another known process according to German Pat. No. 2,726,240 for the dry development of two-component diazocopying material, in particular polyesterbased microfilm-duplicating film, the diazocopying material passes at atmospheric pressure through an ammonia-steam mixture, containing 3-25% by weight of ammonia, at a temperature between about 105.degree. and 120.degree. C. Before the developing atmosphere, the diazocopying material is exposed to a predeveloping atmosphere at a temperature between 100.degree. and 110.degree. C.; the predeveloping atmosphere contains 20 to 80% of the ammonia concentration of the developing gas atmosphere. The apparatus for carrying out this process comprises a developing chamber provided with at least one heating installation which is connected by a temperature control device to a thermometer probe arranged in the developing chamber. The temperature control device is adapted to a set point between 105.degree. and 120.degree. C. At least one line opens into the developing chamber for feeding in the developer. A predeveloping chamber is arranged just before the developing chamber, and a restrictor is situated between these two chambers. The predeveloping chamber is linked to a suction device having a capacity, by means of which the developing gas, streaming in through the restrictor, maintains the ammonia-gas concentration in the predeveloping chamber between 70 and 80% of the ammonia-gas concentration in the developing chamber. The metering devices for the developer are proportioned in such a way that an ammonia-concentration of 3-25% by weight is maintained in the developing chamber. The predeveloping chamber is provided with a heating installation by means of which the predeveloping atmosphere is heated to a temperature between 100.degree. and 110.degree. C. In this developing apparatus, the ante-chambers contribute to a large extent to the development of the diazocopying material which passes through them. Thus the achieveable optical density of the developed diazocopying material is increased.
In the known processes and apparatuses, the expenditure on construction for obtaining a large optical density, for avoiding the precipitation of condensate on the structural parts inside the developing chamber, for lowering the ammonia portion in the spent air and for reducing the ammonia consumption is large and, hence, correspondingly expensive.